Unfortunately, the Cyber Hymnal / Net Hymnal folks store their hymns
as NoteWorthy Composer files (see their FAQ), and the NWC
binary file format has no public specification. Luckily, a number of
brave souls laid the groundwork (source here and
here) for a binary-NWC-to-LilyPond converter. The
original wasn't working for me, so I've put in some time rewriting it
and cleaning things up. I've also merged in Hans de Rijck's 1.0
version.